Distributing element for lubricating systems

ABSTRACT

The present application concerns a distributor element, in particular a feed distributor, for the metering of lubricants for lubricating installations, with a valve piston ( 1 ) featuring a bore ( 2 ), which valve piston moves under the pressure of a lubricant operating at a lubricant inlet ( 6 ) against the force of a first return spring ( 7 ) from a starting position in which the bore ( 2 ) releases a connection between a dispensing chamber ( 3 ) and a metering chamber ( 4 ) via a connecting passage ( 5 ), to a metering position in which the valve piston ( 1 ) releases a passage ( 8 ) from the lubricant inlet ( 6 ) to the connecting passage ( 5 ) and therefore to the metering chamber ( 4 ). Furthermore the distributor element features a dispensing piston ( 9 ) which under the effect of a lubricant entering the metering chamber ( 4 ) moves against the force of a second return spring ( 10 ) from a starting position and thereby pushes the lubricant volume present in the dispensing chamber ( 3 ) between the valve piston ( 1 ) and the dispensing piston ( 9 ) into a lubricant outlet ( 11 ), whereby the valve piston ( 1 ) may also be moved into an intermediate position until equalisation of pressure has occurred, in which position the valve piston blocks the passage ( 8 ) from the lubricant inlet ( 6 ) to the connecting passage ( 5 ) and therefore to the metering chamber ( 4 ) and whereby upon pressure relief at the lubricant inlet ( 6 ), the valve piston ( 1 ) is moved back to its starting position by the first return spring ( 7 ) and the dispensing piston ( 9 ) is moved back to its starting position by the second return spring ( 10 ).

The invention concerns a distributor element, particularly a feeddistributor, for metering lubricants like grease for lubricatinginstallations.

A known lubricant distributor of this type features a valve piston witha bore, which valve piston moves under the lubricant pressure operatingat a lubricant inlet against the force of a single return spring from astarting position in which the bore releases a connection via aconnection passage from a metering chamber to a dispensing chamber, to ametering position in which the valve piston releases a passage from thelubricant inlet to the connecting passage and therefore to the meteringchamber. Additionally, this lubricant distributor has a dispensingpiston which can be moved against the force of the said only returnspring under the effect of lubricant entering the metering chamber. As aresult of the lubricant pressure building up in the metering chamber,the lubricant volume present in the dispensing chamber between the valvepiston and the dispensing piston is pushed into at least one lubricantoutlet and the valve piston is moved by the dispensing piston into anintermediate position until pressure equalisation has occurred, in whichposition the valve piston blocks the passage from the lubricant inlet tothe connecting passage and therefore to the metering chamber. Upon asubsequent pressure relief at the lubricant inlet the valve piston andalso the dispensing piston are returned to their starting position bythe only return spring. A disadvantage of such a distributor element isthat the hydraulic lubricant pressure (working pressure) of e.g. up to250 bar operating at the valve inlet must be reduced to a relatively lowresidual pressure of e.g. about 45 bar for the required pressure reliefto ensure reliable operation.

The known design, in particular if several lubricant distributors areconnected in series, can lead to impaired functioning of the lastlubricant distributor because of pressure reduction occurring in thelubricant line. The problem of a too low relief pressure cannot besolved by strengthening the only return spring provided in this state ofthe art, because this does not only cooperate with the valve piston butin the other direction also with the dispensing piston. A strongerreturn spring would lead to an increase of the pressure which must movethe dispensing piston into its final position.

The purpose of the present invention is to propose a distributor elementof the type described in which the relief pressure (residual pressure)is significantly higher e.g. about twice as high as with the knowndistributor element and yet without an increase of the minimum operatingpressure i.e. the pressure at which the dispensing piston is in itsdisplaced final position.

The invention essentially achieves this purpose with a distributorelement for metering of lubricants like grease, for lubricatinginstallations, featuring a valve piston with a bore which valve pistonmoves under the pressure of a lubricant operating at a lubricant inletagainst the force of a first return spring from a starting position inwhich the bore releases a connection between a dispensing chamber and ametering chamber via a connecting passage to a metering position inwhich the valve piston releases a passage from the lubricant inlet tothe connecting passage and therefore the metering chamber.

Additionally the invention proposes a dispensing piston which under theeffect of lubricant entering the metering chamber moves against theforce of a second return spring so that the lubricant volume present inthe dispensing chamber between the valve piston and the dispensingpiston is pushed into at least one lubricant outlet. The valve pistonmay also be moved into an intermediate position until pressureequalisation has occurred, in which position the valve piston blocks thepassage from the lubricant inlet to the connecting passage and thereforeto the metering chamber. Upon pressure relief at the lubricant inlet thevalve piston is moved back to its starting position by the first returnspring and the dispensing piston is moved back to its starting positionby the second return spring.

Because of the higher residual pressure proposed by the invention,shorter switching times are achieved and lines of greater length and/orsmaller diameter can be used which saves costs. At the same time theminimum operating pressure can be kept low. Spring force and springcharacteristics of the two return springs can be separately dimensionedas a function of the diameter of the pistons, bores and passages.

As we have seen in comparison to the state of the art, the inventionproposes that the only return spring be replaced by two separatelyfunctioning return springs. Now the first return spring only workstogether with the valve piston, whereas the second spring only takescare of the return of the dispensing piston. The dimensioning of thereturn springs can follow depending on the available conditions e.g. asa function of the length and diameter of the lines used, meteringvolumes, operating pressures, residual pressures and the like.

Thus it becomes possible to achieve in a simple manner that the minimumoperating pressure is not increased but can be kept low despite theincrease in the residual pressure.

In a constructionally particularly simple manner the solution as per theinvention can be realised in an embodiment by the fact that anessentially hollow cylindrical supporting body for both return springsis arranged between the first and second return spring. The passage thatmay be present in the supporting body permits an extension of thedispensing piston facing the valve piston so that when the dispensingpiston is actuated by the pressure built up in the metering chamber, thevalve piston can first be moved by the dispensing piston into anintermediate position in relation to its starting position in which thelubricant inlet is separated from the connecting passage.

In a further embodiment of the invention the valve piston, dispensingpiston, supporting body and the two return springs are arranged in amutually axial configuration in a common straight passage of a valvehousing In order to simplify the manufacture and improve thefunctionality.

Advantageously, in order to save space and provide reliable support, thesecond return spring is a spiral coiled spring mounted around thedispensing piston.

In another embodiment of the invention the fact that the second returnspring, being a spiral coiled spring, is in any case with the end thatfaces the valve piston, mounted around the first return spring which isalso a spiral coiled spring, achieves that at a specified length of thereturn springs the total length of the distributor element can be short.

In this situation it is advantageous if the first return spring being aspiral coiled spring is housed with the end that faces the dispensingpiston in a cylindrical supporting body which is surrounded by thesecond return spring which is also a spiral coiled spring. The firstreturn spring can then be braced on a radially inward projecting flangeat the end of the cylindrical supporting body opposite the valve pistonand is accommodated in the cylindrical supporting body. Conversely thesecond return spring can rest against the outside of the cylindricalsupporting body and be braced on a radially outward projecting bottomflange of the cylindrical supporting body.

The supporting body itself can rest against a bearing shoulder of thevalve housing facing away from the valve piston.

Further purposes, features, advantages and application possibilities ofthe invention become clear from the following description of embodimentswith reference to the drawings. Hereby all features described and/orgraphically displayed, individually or in any combination, are thesubject of the invention, also independent of their being summarised inindividual claims or their cross-reference.

FIG. 1 Partial section through the longitudinal centre plane of a valveelement designed as a feed distributor as proposed by the invention inaccordance with an embodiment.

FIG. 1A Side view of the dispensing piston taken from FIG. 1.

FIG. 1B ₁ Side view and top view of the supporting body taken from FIGS.1 and

1B₂ Representation as per FIG. 1 of another embodiment of a distributorelement as per invention and

FIG. 2 Representation of the detail IIA from FIG. 2

FIG. 2A

The feed distributor for metering lubricants e.g. grease shown in thedrawings for feed lubricating installations has a distributor housing 14with a passage 13 extending over the length of the housing 14. In thelower end of the housing 14 a sealing element 16 with a lubricant inlet6 is screwed in. The lubricant inlet 6 opens on to an axial inletpassage 6′ that leads to valve piston 1. This valve piston is axiallydisplaceable in the passage 13 and is braced on the side opposite thelubricant inlet 6 on the first return spring 7 which is coaxiallyarranged in the passage 13. The first return spring 7 rests with its endthat is opposite the valve piston 1 against a hollow cylindricalsupporting body 12 which is axially fixed in a defined position in thepassage 13 by means of threaded connection 17 and bearing shoulder 22.

In FIG. 1 the valve piston 1 is in its intended starting position at thebeginning of a lubricating cycle, which position the valve piston 1reaches at the end of the preceding lubricating cycle and in alubricating interval that may follow. In the embodiment shown the valvepiston 1 has a transverse bore 2 which on one side communicates via anaxial bore section with a dispensing chamber 3 in the passage 13 beforethe valve piston 1 and on the other side via a radial bore section witha passage 8 radially aligned in the valve housing 14 and whereby thispassage 8 leads into a connecting passage 5 longitudinally extendingparallel to the connecting passage 3.

The connecting passage 5 leads at its upper end i.e. the end oppositethe valve piston 1 into a metering chamber 4 which inside the passage 13is delimited in relation to the valve piston 1 by a dispensing piston 9equipped with a peripheral seal 17. The dispensing piston 9 is bracedtowards the valve piston 1 by means of a second return spring 10 on theside of the supporting body 12 opposite the valve piston 1.

In the starting position shown in FIG. 1 the dispensing piston 9 mayextend into an upper laterally open sealing body with a check pin forvisual function display. Towards the valve piston 1 the dispensingpiston 9 may have an extension 20 to enable the valve piston 1 to firstmove into an intermediate position at the end of the lubricating cyclebefore reaching its starting position as described below. The valvehousing 14 has at least one lubricant outlet 11 which in the startingposition of the valve piston 1 shown in FIG. 1 is situated immediatelybefore the front end of the valve piston facing the dispensing piston. Alubricant passage 11′ equipped with a screw plug 21 may serve forfilling the distributor element with lubricant.

The working of the distribution element invented is as follows:

In the lubricant interval phase shown in FIG. 1 the pressure operatingat the lubricant inlet 6 of the distributor element has been reduced toa residual pressure. The two return springs 7, 10 are relaxed to therelevant desired and accordingly dimensioned initial tension. Thedispensing chamber 3—after the first fill through a lubricant passage11′—is filled with lubricant by the preceding lubricating cycle. Thetransverse bore 2 still connects the dispensing chamber 3 with themetering chamber 4 via the connecting passage 5.

At he beginning of the pressure reduction and lubricating phase acentral lubricating pump may build up the lubricant pressure in the mainline and in the lubricant inlet 6, 6′ to an operating pressure. Thevalve piston 1 is pushed forward by the operating pressure against theforce of the first return spring 7 until it releases the passage 8 tothe metering chamber 4 in the valve housing 14 via the connectingpassage 5. The lubricant supplied by the lubricant inlet 6 then reachesthe metering chamber 4 via the connecting passage 5. The lubricantpressure developing in the metering chamber 4 acts on the dispensingpiston 9 which is actuated against the force of the second return spring10. Simultaneously the check pin section 18 if provided is pulled in.While the metering chamber 4 is filled up on one side of the dispensingpiston 9, the dispensing piston displaces on the other side a meteredlubricant volume under lubricant pressure from the dispensing chamber 3against the force of the second return spring 10 to the open lubricantoutlet 11. A lubrication manifold (not shown) is connected to thelubricant outlet 11. In the lubricating phase the hydraulic operatingpressure of the lubricating pump has a preset minimum value of e.g. 250bar.

At the completion of the lubricating phase the dispensing piston 9 hasdisplaced the metered lubricant volume from the dispensing chamber 3 tothe lubricant outlet 11 (or 11′) and, if so equipped, has moved by meansof its extension 20 the valve piston 1 to an intermediate position inwhich the passage 8 to the connecting passage 5 is blocked by the rearpart of the valve piston 1. The distributor element remains in thisposition until a pressure relief valve on the lubricating pump isactuated.

In order to make it possible for the distributor element to reverse, thelubricant line between the lubricating pump and the lubricant inlet 6 ofthe distributor element is depressurised at the completion oflubrication in a subsequent pressure relief phase. If the first returnspring 7 is dimensioned accordingly, a smaller pressure reduction to adesired residual pressure of e.g. 90 bar (compared to 45 bar for theusual distributor elements) is sufficient. The first return spring 7then pushes the valve piston 1 from the intermediate position firsttaken up (downward) into the final position shown in FIG. 1(representing the starting position for the following lubricatingcycle). Now the metering chamber 4 is connected again with thedispensing chamber 3 via the connecting passage 5, the released passage8 and the bore 2.

The second return spring 10 can now transfer lubricant present in themetering chamber 4 to the dispensing chamber 3 and fill it using theabove route. When the dispensing piston 9 has reached its upper finalposition as shown in FIG. 1 through the action of the second returnspring 10, the distributor as a whole has returned to its startingposition in this lubricating cycle and a new cycle can begin. The ratingof the second return spring 10 independent of the first return spring 7ensures the desired low minimum operating pressure.

The basic functioning of the embodiments shown in FIGS. 2 and 2A of adistributor element as per invention is not different from thedistributor element shown in the FIGS. 1 to 1B2. However, where theconstruction of this distributor element is different is the fact thatthe supporting body 12 is designed as an elongated cylindrical bodycoaxial with the two return springs 7 and 10 and that this bodyaccommodates the top part of the first return spring 7. The first returnspring 7 is braced at a radially inward projecting flange 24 at theupper end of the supporting body 12 opposite the valve piston 1.Conversely, the second return spring 10 surrounds the cylindrical body12 with its end that faces the valve piston 1 and is braced on aradially outward projecting bottom flange 23 of the supporting body 12.In this manner the two return springs 7, 10 can be relatively long andhave appropriate spring characteristics despite the length of thedistributor element remaining the same.

List of Reference Symbols

-   1 Valve piston-   2 Bore-   3 Dispensing chamber-   4 Metering chamber-   5 Connecting passage-   6,6′ Lubricant inlet, lubricant inlet passage-   7 First return spring-   8 Passage-   9 Dispensing piston-   10 Second return spring-   11,11′ Lubricant outlet or passage-   12 Supporting body-   13 Passage-   14 Valve housing-   15 Threaded connection-   16 Lower sealing body-   17 Peripheral seal-   18 Check pin section-   19 Upper sealing body-   20 Extension-   21 Screw plug-   22 Bearing shoulder-   23 Bottom flange-   24 Flange

1-8. (canceled)
 9. Distributor element, in particular a feeddistributor, for the metering of lubricants for lubricatinginstallations, with a valve piston (1) featuring a bore (2), which valvepiston moves under the pressure of a lubricant operating at a lubricantinlet (6) against the force of a return spring (7) from a startingposition in which the bore (2) releases a connection between adispensing chamber (3) and a metering chamber (4) via a connectingpassage (5), to a metering position in which the valve piston (1)releases a passage (8) from the lubricant inlet (6) to the connectingpassage (5) and therefore to the metering chamber (4); and furthermorethe distributor element features a dispensing piston (9) which under theeffect of a lubricant entering the metering chamber (4) moves againstthe force of a second return spring (10) from a starting position andthereby displaces the lubricant volume present in the dispensing chamber(3) between the valve piston (1) and the dispensing piston (9) through alubricant outlet (11), whereby the valve piston (1) may also be movedinto an intermediate position in which position the valve piston blocksthe passage (8) from the lubricant inlet (6) to the connecting passage(5) and therefore to the metering chamber (4) and whereby upon pressurerelief at the lubricant inlet (6), the valve piston (1) is moved back toits starting position by the first return spring (7) and the dispensingpiston (9) is moved back to its starting position by the second returnspring (10).
 10. Distributor element as claimed in claim 9, wherein anessentially hollow cylindrical supporting body (12) for the two returnsprings (7, 10) is arranged between the first return spring (7) and thesecond return spring (10).
 11. Distributor element as claimed in claim9, wherein the valve piston (1), the dispensing piston (9), thesupporting body (12) and the two return springs (7, 10) are arranged ina mutually axial configuration in a common passage (13) of a valvehousing (14).
 12. Distributor element as claimed in claim 9, wherein thesecond return spring (10) is a spiral coiled spring surrounding thedispensing piston (9).
 13. Distributor element as claimed in claim 9,wherein the second return spring (10) which is a spiral coiled spring inany case with its end facing the valve piston (1) surrounds the firstreturn spring (7) which also is a spiral coiled spring.
 14. Distributorelement as claimed in claim 9, wherein the first return spring (7) inthe form of a spiral coiled spring, is accommodated with its end thatfaces the dispensing piston (9) in a cylindrical supporting body (12)which is surrounded by the second return spring (10) that also is aspiral coiled spring.
 15. Distributor element as claimed in claim 14,wherein the second return spring (10) is braced on a bottom flange (23)of the supporting body (12).
 16. Distributor element as claimed in claim9, wherein the supporting body (12) is braced on a bearing shoulder (21)of the valve housing (14), this shoulder being at the opposite end fromthe valve piston (1).
 17. Distributor element as claimed in claim 10,wherein the valve piston (1), the dispensing piston (9), the supportingbody (12) and the two return springs (7, 10) are arranged in a mutuallyaxial configuration in a common passage (13) of a valve housing (14).